Back to EveryPatent.com
United States Patent |
5,258,676
|
Reinhardt
,   et al.
|
November 2, 1993
|
Drive unit for double fan
Abstract
The invention relates to a drive unit for a double fan consisting of two
external rotor motors (1, 2) arranged alongside each other on a common
motor shaft (3), wherein the external rotor motors (1, 2) are arranged
with respect to each other in such a way that the poles of the stators
(12) of the two motors (1, 2) and the poles of the rotors (7) of the two
motors lie in mirror image symmetry with respect to each other with
reference to a dividing plane X--X running between the two external rotor
motors (1, 2) at right angles to the motor shaft (3).
Inventors:
|
Reinhardt; Wilhelm (Schrozberg-Gutbach, DE);
Muller; Werner (Mulfingen-Seidelklingen, DE)
|
Assignee:
|
ebm Elektrobau Mulfingen GmbH & Co. (DE)
|
Appl. No.:
|
880238 |
Filed:
|
May 8, 1992 |
Foreign Application Priority Data
Current U.S. Class: |
310/112; 310/67R |
Intern'l Class: |
H02K 007/20 |
Field of Search: |
310/112,66,67 R,156,254,258,261
|
References Cited
U.S. Patent Documents
2700343 | Jan., 1955 | Pezzillo | 310/112.
|
2976352 | Mar., 1961 | Atalla et al. | 230/117.
|
3083893 | Apr., 1963 | Dean et al. | 230/117.
|
3175755 | Mar., 1965 | Rockafield | 230/117.
|
4010716 | Mar., 1977 | Minka | 123/8.
|
4571528 | Feb., 1986 | McGee et al. | 310/156.
|
4612468 | Sep., 1986 | Sturm et al. | 310/67.
|
Foreign Patent Documents |
0100078 | Feb., 1984 | EP | 310/112.
|
0273482 | Jul., 1984 | EP | 310/112.
|
0310391 | Apr., 1989 | EP | 310/112.
|
0447257 | Sep., 1991 | EP | 310/112.
|
1198955 | Aug., 1965 | DE | 310/112.
|
1428063.8 | Nov., 1968 | DE | 310/112.
|
1538901.2 | Dec., 1969 | DE | 310/112.
|
2732763 | Jan., 1979 | DE | 310/112.
|
363119 | Aug., 1962 | CH | 310/112.
|
658299 | Dec., 1978 | CH | 310/112.
|
1199497 | Jul., 1970 | GB | 310/112.
|
Primary Examiner: Stephan; Steven L.
Assistant Examiner: Nguyen; Matthew
Attorney, Agent or Firm: Jones & Askew
Claims
We claim:
1. Drive unit for a double ventilator including two electrical external
rotor motors (1, 2) arranged side by side on a motor shaft (3), where the
electrical external rotor motors (1, 2) each have a rotor and a stator and
are each arranged with respect to each other so that the poles of the
stators of the two motors (1, 2) and the poles of the rotors (7) of the
two motors, respectively, lie in a mirror-symmetric configuration with
respect to a separation plane (X--X) running between the two motors (1, 2)
and perpendicular to the motor shaft (3), comprising in combination:
each of the stators (12) has at least one stator winding (14) forming at
least two poles of opposing polarity in the respective stator (12);
the motor shaft (3) runs inside a bearing support tube (4);
the stators of the two motors (1, 2) have laminated cores that are rigidly
attached to the support tube (4);
the separation plane (X--X) runs through a gap (18) between the two motors
(1, 2);
a circuit board (19) for components of control circuitry of the two motors
(1, 2) is located inside the gap (18); and
a fastening flange (22) perpendicular to the motor shaft (3) is in the gap
(18), the fastening flange being formed in one piece with the bearing
support tube (4).
2. Drive unit according to claim 1, characterized in that at both sides of
the motor shaft (3) the rotor of one of the motors (1, 2) is fastened with
a connection by means of a rotor bushing (8, 9).
3. Drive unit according to claim 1, characterized in that the fastening
flange (22) is selected from the group consisting of individual radial
spokes spaced according to the circumference of the motor and a continuous
flange plate with intermittently formed openings for wires extending to
the windings.
4. Drive unit according to claim 1, characterized in that fastening
elements (25) are formed on an outer side of the fastening flange (22) for
fastening the drive unit to a housing (24).
5. Drive unit according to claim 1, characterized in that the rotors have
housings (11) with an outer side to which fastening brackets (26) are
provided, and fan impellers (27) are attached to the fastening brackets.
6. Drive unit according to claim 1, characterized in that the rotors have
housings (11) with an outer side to which fan impellers (27) are directly
attached.
7. Drive unit according to claim 1, characterized by a ventilator housing
(24) holding the motors (1, 2) and having a central housing wall (28) and
left and right housing walls (29, 30) as well as upper and lower housing
walls (31), and air entry openings (32) formed in the upper and lower
housing walls (31).
8. Drive unit according to claim 7, characterized in that the air entry
openings (32) are arranged concentrically to the motor shaft (3) and that
the central housing wall (28) divides the housing (24) into two housing
halves, and the central housing wall (28) has a central opening (33), in
which the motors (1, 2) are attached by the fastening flange (22).
Description
This invention relates to a drive unit for a double fan.
DE-OS 15 38 901 discloses a drive for devices with several rotation speeds
in which the two electric motors are included together with a common
mounting in a unit provided with a common output shaft and the rotors of
the motors are constructed as external rotors. This drive unit can thus
drive e.g. the washing drum of a washing machine at four different
rotation speeds even though the motor is designed for two rotation speeds.
It provides an economical and compact construction for the drive unit.
In the case of drives for double fans, i.e. fans with two separate
impellers, the driving motor must have a relatively large power and
therefore large motor dimensions. Large motor dimensions however reduce
the cross-section available for the intake of air for given fan
dimensions, so that high rotation speeds must be used. The consequences
are a relatively poor efficiency, reduced service life and increased
manufacturing costs. In addition to this, when a single motor is used,
there is no uniform distribution of the air stream to the two impellers
because of the asymmetries brought about by the motor fastenings on one
side. If two separate motors are used to drive the two impellers of a
double fan then these two motors must be synchronised electronically, and
this likewise results in an increased investment in circuitry. The drive
unit disclosed in DE-OS 15 38 901 is unsuitable for driving double fans,
since it is not possible to drive the output shaft by both motors at the
same time.
The object of this invention is to provide a drive unit for a double fan
which is both compact and economical to manufacture and also has two motor
units which both run in absolute synchronism.
In accordance with the invention a drive unit for double fans comprises two
external rotor motors located alongside each other on a common motor shaft
in such a way that the external rotor motors are arranged together so that
the poles of the stators of the two motors and the poles of the rotors of
the two motors lie in mirror image symmetry to each other with reference
to a dividing plane running between the two external rotor motors at right
angles to the motor shaft. Through this arrangement of the drive unit in
accordance with the invention the two drive motors can be provided with a
smaller external diameter than would be the case if a single motor were
used, so that the intake of air is improved. In addition to this the
lengths of the windings for the individual motors are shorter than the
windings of a single motor, with the result that the motors are easier to
wind.
In addition, efficiency is improved in comparison with the use of a single
motor, since heat can be removed more easily from the smaller motors. As a
result of the improved heat removal the motor bearings run at lower
temperatures, which results in a longer service life for the bearing
system and therefore the motor. The investment in electronics is
appreciably reduced in comparison with the use of two separate motors, as
absolute synchronism can be achieved through the arrangement according to
the invention without separate electrical control.
Further advantageous embodiments of the invention are included in the
subsidiary claims.
The invention will now be more particularly described with reference to the
embodiments illustrated in the appended drawings. These show:
FIG. 1 a longitudinal cross-section through a drive unit according to the
invention.
FIG. 2 a partial cross-section through a double fan with a drive unit
according to FIG. 1.
As may be seen from FIG. 1, a drive unit according to the invention
comprises two external rotor motors 1, 2 which are mounted alongside each
other on motor shaft 3. Hence motor shaft 3 runs through a common bearing
mounting tube 4 for the two motors and is mounted at the ends in bearings
5, in particular ball races, secured in bearing mounting tube 4 by means
of bearing bushes 6. The rotor 7 of one of motors 1, 2 is secured to the
terminal ends of motor shaft 3 projecting beyond bearing mounting tube 4
by an interference and/or interlocking fit by means of a rotor bush 8. The
right hand rotor bush 8 in FIG. 1 is here pressed onto the end of motor
shaft 3, while left hand rotor bush 9 is releasably secured.
The two rotors 7 are constructed in a bucket-shape cross-section wherein
rotor bushes 8, 9 are each secured to the base 10 of rotors 7. Rotors 7
have a surrounding rotor wall 11 which concentrically surrounds the stator
12 of motors 1, 2. Each of the stators 12 has a laminated stator core 13
and a stator winding 14. Stators 12 are fixed for example by means of
pressure fitting, with their laminated cores 13 on bearing mounting tube
4. End discs 15 of an electrically insulating material are provided at the
ends of stator laminated core 13. A radially magnetized strip-shaped
permanent magnet 17 is secured to the inside of rotor wall 11 of rotors 7
and this has at least two opposite polarities, namely a north pole and a
south pole. Magnetic segments can be used as an alternative. Stator
winding 14 of each stator 12 is wound in such a way that at least two
poles of opposite polarity can be formed within the stator. Advantageously
a 6-pole rotor is used in combination with a three strand stator winding.
A plane of symmetry or dividing plane X--X lies at right angles to motor
shaft 3 between motors 1, 2 which lie alongside each other in a axial
direction. This dividing plane X--X runs through a gap 18 lying between
the motors. Stators 12 of the two motors 1, 2 and rotors 7 of the two
motors 1, 2 are arranged together in such a way that their poles lie in
mirror image symmetry with respect to dividing plane X--X, i.e. the pole
of the stator of the motor 1 and the pole of the stator of motor 2 are in
mirror image symmetry with respect to each other and dividing plane X--X
and the pole of rotor 7 of motor 1 is in mirror image symmetry to the pole
of rotor 7 of motor 2 with respect to dividing plane X--X. This
symmetrical arrangement of the poles is maintained when motors 1, 2 are
stationary and running so that the two motors run absolutely
synchronously. In addition to this a printed circuit board 19 is located
in gap 18 between the two motors, and this bears the sensors required to
detect the rotor position and the circuits for the windings of the two
stators. As a result of the configuration of the drive unit according to
the invention only one set of control electronics is necessary so that a
common voltage supply and control electronics are provided for the two
motors. An electrical conductor 20 which is introduced into the drive unit
via gap 18 is connected to printed circuit board 19.
In addition to this it can be seen from FIG. 1 that a securing flange 22
runs through gap 18 at right angles to motor shaft 3 and is integrally
attached to bearing mounting tube 4. This securing flange 22 may consist
of individual spaced radial spokes or a through flange plate with openings
in places for the wires of the winding to pass through. In addition
securing flange 22 has securing members 25 on its outside to secure the
drive unit to a housing 24, see FIG. 2. As a result of this configuration
in accordance with the invention the drive unit according to the invention
is mounted in a housing without any problems because there is a balanced
distribution on either side of the securing flange.
As shown in FIG. 2, securing brackets 26 are provided on the outside of
rotor walls 11 of rotors 7. These securing brackets 26 can be shrunk on to
the periphery of the rotor or secured by other means. Fan impellers 27 can
be secured to securing brackets 26 in a known way. The scope of the
invention also includes the direct attachment of these fan impellers to
rotors 7.
As can be seen from FIG. 2, a fan housing 24 according to the invention
comprises a central housing wall 28 and a left and a right housing wall
29, 30 and upper and lower housing walls 31, which incorporate air intake
openings 32. These intake openings 32 are concentric with motor shaft 3.
The size of intake openings 32 depends on the diameter of the fan
impellers 27. Central wall 28, which effectively divides the housing into
two halves, consists of a triangular sheet which is bent at its outer
edges for reasons of stability, and which is secured to housing 24 in the
vicinity of its edges. A central opening 33 is provided in central wall 28
in which motors 1, 2 are located on the securing flange in such a way that
central wall 28 falls along the dividing plane X--X for the drive unit.
The front and rear ends of fan housing 24 form two opposite air outlet
openings which extend over the full height of the fan housing.
As will be seen from the above, this yields a very compact construction for
a double fan and also allows the drive unit to be fitted without
difficulty.
Top